Showing papers by "University of Iceland published in 1984"

T‐cell subpopulations in the blood and skin of patients with psoriasis

Abstract: SUMMARY Monoclonal antibodies were used to determine, simultaneously, the proportions of T-cell populations in the peripheral blood and in the skin lesions of fifty-one patients with psoriasis. The results were analysed in relation to the extent, age and clinical type of the skin lesions. In the group of patients with extensive lesions, a significant reduction in the number of total T (TT) and T helper/inducer-cells, (TH), but not in T suppressor/cytotoxic cells (Ts) was observed in the peripheral blood. Furthermore, the skin TH/TS ratio was greater in late guttate and in chronic plaque lesions than the corresponding ratio in the blood. These findings suggest that there is an active selective recruitment of TH cells into established psoriatic lesions. In contrast, the TH/TS ratio in early guttate lesions was the same as in the blood, and significantly lower than in the plaque lesions. An additional finding was a decrease of TS, and a corresponding increase of null cells in the blood of patients with chronic plaque psoriasis. These observations provide further evidence for the participation of T cells in the pathogenesis of psoriasis.

Widening of the Krafla fissure swarm during the 1975–1981 volcano-tectonic episode

Abstract: Frequent distance measurements across the Krafla fissure swarm, North Iceland, recorded the extension accompanying the sequence of rifting events which started in December, 1975, and lasted for 6 years. An 80 to 90 km long section of the fissure swarm extended during this sequence of rifting and volcanic events. Maximum widening of about 8 m occurred 10 to 12 km north of Leirhnjukur. which is located above the center of the Krafla magma reservoir. From that location, the amount of widening decreased north-wards and is estimated to exceed 2 m where the seismicity indicated the northern termination of the present rifting, off the north coast, about 70 km north of Leirhnjukur. The amount of widening also decreased southwards and approached zero at 15 to 20 km south of Leirhnjukur. The ground deformation associated with these rifting events can be summarised as: A narrow strip, 1 to 2 km wide, along the fissure swarm is heavily fractured with numerous open cracks parallel to the fissure swarm. This fractured strip has subsided 2 to 3 m relative to its flanks. The flanks of the fractured zone have been uplifted relative to regions farther away. The uplift is not well constrained, but tilt observations at several locations indicate about 1 m uplift. The flanks of the rift zone have contracted, perpendicular to the fissure swarm. The maximum contractional strain exceeds 300 mm per km. The amount of areal expansion (windening of the fissure swarm times the length of the fractured zone) associated with these rifting events is estimated to be about 0.30 km2. For individual events, the area of expansion has been roungly proportional to the volume of subsidence above the Krafla magma reservoir. If the width of a new dike is equal widening of surface fissures, the ratio of the subsidence volume to the area of expansion for the best observed events indicated a height of a new dike system as 2.4 to 2.8 km. This ratio is significantly less for events of large lava production, but even during these events, the majority of magma leaving the Krafla reservoir was apparently emplaced in subsurface fissures.

Abnormal Metabolism of γ-Trace Alkaline Microprotein : The Basic Defect in Hereditary Cerebral Hemorrhage with Amyloidosis

Abstract: ALTHOUGH the total incidence of cerebral hemorrhage is high, comparatively few reports concerning the familial occurrence of this disease have been published.1 , 2 In 1935 Arnason described 10 fami...

Anomalous focal mechanisms: tensile crack formation on an accreting plate boundary

Abstract: Conventional double-couple solutions do not satisfactorily account for many small magnitude earthquakes in the Hengill geothermal area in the Neovolcanic Zone of Iceland. The far-field radiation pattern is predominantly compressional but a few dilatational arrivals have been recorded. We prefer the interpretation that these events are due to tensile crack formation at a shallow (1–7 km) depth within a cooling intrusive body. Volume considerations indicate that initial fracturing of the rock is seismic but that subsequent widening proceeds aseismically. Other reports of anomalous radiation patterns from earthquakes on the Mid-Atlantic Ridge describe events of a similar type, that is, exhibiting predominantly compressional radiation patterns and a reduced dilatational field1–4.

Hypodontia, hyperodontia, and double formation of primary teeth in Iceland An epidemiological study

Abstract: The aim of this study was to determine the prevalence of hypodontia, hyperodontia, and double formation of primary teeth in Icelandic children in the dental stage DS 02 (primary dentition complete). The study group comprised 927 children (498 boys and 429 girls). This was about 9% of all children aged 0-83 months in Reykjavik at the time of the registration of these anomalies, during the winter of 1978-1979. The children included those presenting for regular examinations in two health centers, children from three kindergartens, and seven pre-school classes from two schools in Reykjavik. Of these children 61.9% were selected for this study as they proved to be in dental stage DS 02 (primary teeth fully erupted). The prevalences were hypodontia, 0.5%; hyperodontia, 0.5%; and double formation, 0.7%. Comparison was made with earlier results from Iceland and with results from several other nations.

Crown size of deciduous teeth in Icelanders

Abstract: Mesiodistal and buccolingual crown diameters of deciduous teeth were measured from dental casts of 540 Icelandic children Statistically significant sexual dimorphism was present in five of the buccolingual and in six of the mesiodistal diameters The variability of the measurements followed the field concept but did not show systematic sexual dimorphism In accordance with the permanent teeth, the size of the deciduous teeth also proved to be at the top of the range for populations of European origin

Maternal Beta-Adreneceptor Blockade Reduces Fetal Tolerance to Asphyxia: A study in pregnant sheep

Abstract: Maternal and fetal β1-adrenoceptor blockade was induced in sheep by infusing i.v. 11 pregnant ewes with metoprolol in doses producing maternal plasma concentrations of metoprolol comparable to those obtained in clinical use. Ten other ewes and their fetuses served as controls. Under acute anaesthesia the fetus was exteriorized and subjected to two levels of controlled asphyxia by intermittent, complete obstruction of the maternal placental blood flow. Fetal haemodynamic reactions were assessed by measuring fetal heart rate, cardiac contractility, cardiac output and cerebral blood flow. The metabolic reactions were evaluated from blood gases, pH, lactate and hypoxanthine concentrations, while the electrophysiological status of the brain was evaluated from the somatosensory evoked EEG potentials (SEP). Already during the period of moderate asphyxia the P-blocked fetuses demonstrated a blunted haemodynamic response, in comparison with the control fetuses, resulting in an accelerating lactic acidosis, signs o...

On the length of simplex paths: The assignment case

Abstract: This paper reports on an experimental study of the distribution of the length of simplex paths for the Optimal Assignment Problem. We study the distribution of the pivot counts for a version of the simplex method that with essentially equal probabilities introduces any variable with negative reduced cost into the basis. In this situation the distribution of the pivot counts turns out to be normally distributed and independent of the actual cost coefficients, provided these are sufficiently spread out. Further, the mean and standard deviation grow only moderately with the size of the problem, namely asd1.8, andd1.5 respectively for ad×d problem, implying in particular that the pivot counts concentrate around the mean with growingd. The usual simplex method on the other hand gives a growth ofd1.6. Hence a large part of the favourable polynomial growth experienced on practical problems may be attributed to the fact that the simplex paths are rather short on the average, at least for assignment problems.

Late determinants of cancer.

Abstract: Summary The paper reviews some findings on the frequency of latent carcinoma. Latent carcinomas are found much more frequently in the prostate, than would be expected from mortality or incidence data. The same applies to neuroblastomas in the adrenal cortex in infants. The problem has not been studied in detail in other organs. A satisfactory explanation of spontaneous regression of human cancers or the variable disease-free survival time of cancer patients has not been found. It is concluded that defence mechanisms of paramount importance exist, and need to be studied. Recent reports on serum retinol and serum cholesterol are reviewed since these are both lower in people who later develop cancer. Much more knowledge is needed but these phenomena could be linked.

On the Locality Ideal In the Algebra of Test Functions for Quantum Fields

Abstract: Some basic properties of the locality ideal in Borchers's tensor algebra are established. It is shown that the ideal is a prime ideal and that the corresponding quotient algebra has a faithful Hilbert space representation. A topology is determined for which the positive cone in the quotient algebra is normal, and it is shown that every w-point distribution satisfying the locality condition is a linear combination of positive functional which also satisfy that condition.

A Medical Record and Information System for Primary Health Care in Iceland: The Egilsstadir Project

Abstract: In Iceland a problem oriented medical record system for primary health care has been developed. A contact-form is used to record data on all contacts between the inhabitants in a district and the health center. A minicomputer is used for retrieval and analysis. One rural health center using this system has been successful in recording a basic set of data on all contacts taking place since 1976 and linking these data to the national register data for the population in the district. Most health centers in Iceland are now adopting this system, because it seems to be: 1. A valuable aid in the treatment of patients, which improves the quality of the treatment. 2. A useful source of information of the health of the population, which among other things makes possible the identification of those at special risk. 3. A good instrument for research and teaching. 4. A useful source of statistics on the primary care services.